Propeller



Patented Mar. 29, 1927.

UNITED STATES WILLIAM STELLNER, 0F COLLINGWOOD, MELBOURNE, VICTORA, AUSTRALIA.

PROPELLER.

Application filed January 4, 1926, Serial No.

This invention relates to propcllers and more particularly to screw type propellers for marine work.

The object of the invention is to provide an improved propeller of the above type which is extremely simple in design and construction, highly efficient in operation, and reduces vibration and power losses to a minimum.

The invention resides primarily in a screw propeller having a plurality of inclined blades, each of which constitutes a sector of a circle defined by the outer edges or tips of the blades, the combined frontal area of said lblades being substantially equal to a complete circular area bounded on the outside by the tips of the propeller blades and on the inside by the peripheral surface of the propeller hub. In other words the blades of the propeller form sectors of a complete circle, so that if placed together in a flat state with Vtheir side edges abutting the blades would form a complete disc as hereinafter described.

Referring to the drawings which form part of this specieationr- Figure l is a diagram illustrating by dot and dash lines the subdivision of a complete circle or disc to form a six bladed propeller in accordance with the invention.

Figure 2 is a front View on a larger scale of a six bladed propeller in accordance with the invention.

Figure 8 is a fragmentary section taken approximately on the line A-A of Figure 2.

Figure 4 is a plan of Figure 2.

Figure 5 is a fragmentary view of a single propeller blade according to a preferred construction.

Figure 6 is a section on line B-B of Figure 5.

Figure 7 is a section on line C--C of Figure 5. l

Figure 8 is a section on line D-D of Figure 5.

Figure 9 is a plan of a modification.

"(9,152, and in Australia February 2G, 3.925:

the width or length of said hub as shown. The corners of Jthe blades are preferably rounded as at S.

As seen in Figures 3, 4 and 9, the blades are inclined at a suitable angleV to the axis of the propeller shaft 9, thereby forming openings or passages, indicated at l0, between the adjacent blades as clearly seen in Figure These openings or passages gradually decrease in area from the outer to the inner ends of the blades and are thusl substantially V shaped when viewed from the front of the propeller as in Figure 2. It will here be seen that the openings l() are relatively narrow and of considerably7 less width than the Width of the blades.

The width of the passages or spaces l0 between the blades depends solely upon the inclination or pitch of said blades, the width and formation of which is such that they forni sectors of a complete circle or disc indicated in Figure l where the radial broken lines (ai) indicate the side edges of the propeller blades and the dotted circle (b) indicates the periphery of the propeller hub. The circular area between this dotted hub circle (b) and the outer circle (c) which coincides with the tipsof the blades, is substantially equal to the combined frontal area of all the blades of the propeller, or, in other words. if all the blades were placed flat or in the same circumferential plane at right angles to the propeller axis and with their side edges abutting, they would form a complete disc. By this characteristie constructional feature, a maximum effective blade area is provided within a 1nini mum space and it has been proved by practical tests that a propeller construct-ed in the manner indicated provides a marked increase in eliieiency, both as regards greater thrust and reduced vibration, as compared with existing propellers.

The front face l1 of each propeller blade in accordance with the invention is preferably fiat as shown whilst the rear face 12 is preferably rounded or bevelled at the side edges of the blade as indicated at 13 in Figures 3, 6 and 7. Furthermore, each blade preferably decreases gradually in thickness from its narrow rootportion 6 to its tip, as shown in Figure 8.

Referring now to the modification illustrated in Figure 9, the blades of the improved propeller may, if desired7 be arranged alternately out of circumferential alignment or in dillerent longitudinal or axial positions upon the hub 7. Figure 9 illustrates a six bladed propeller having its blades arrangeiil in this manner and corresponding in frontal appearance with the propeller seen in Figures 2 and 4, that is to say, that although the alternate blades are arranged in dilt'erent longitudinal positions on the propeller' axis, the aforesaid Vcharacteristic feature relative to the width and sectoral shape et' the blades as described with reference to Figures l and 2, also applies to the modiiied construction illustratedin Figure 9.

As the improved propeller rotates the water or liuid is forced through the passages or openings l0 and across the front and rear faces ot the inclined blades to thereby effect propulsion, the formation and arrangement of the blades as aforesaid, being such as to ensure a maximum forward thrust and a minimum of vibration and power losses.

It will be understood that the characteristic features of this invention as defined by the appended claims may be applied to a propeller having any desired multiplicity ot sectoral blades which may be stamped or cut trom a metal disc as indicated for instance in Figure l or may be formed by casting or otherwise as desired.

Having now described my invention what I claim as new and desire to secure by Letters Patent is l. A marine propeller comprising a hub; and a plurality ot inclined blades on said hub. each of which constitutes a sector of a circle delined by the outer edges or tips of the blades, the combined frontal area of said blades being substantially equal to the complete circular area between said outer edges of the blades and the periphery ot the propeller hub the blades being arranged in sets on said hub.

2. A marine propeller comprising a hub; and a plurality ot inclined blades on said hub which constitute equal sectors of a circle delined by the outer edges or tips ot the blades, the combined frontal area et said blades being substantially equal to the complete circular area between said outer edges ot the blades and the periphery of the propeller hub, the side edges ot said blades converging radially inwards from an arcuate outer edge to the propeller hub, so that, owing to the inclination ot said blades to the propeller axis, relatively narrow inwardly conifei'ging openings or passages are formed between adjacent blades, the width ot said openings being less than that ot the blades and being determined solely by the inclination ot said blades to the propeller axis, and the blades being arranged in sets on said hub.

3. A marine propeller comprising a hub; and a plurality of inclined blades each ot which constitutes a sector of a circle delined by the outer edges or tips of the blades, the combined frontal area ot said blades being substantially equal to the complete circular area between said outer edges of the blades and the periphery of the propeller hub, the alternate blades of said propeller being arranged in different longitudinal or axial positions upon the propeller hub to constitute sets ot blades.

In testimony whereof I affix my signature.

IVILLIAM STELLNER. 

